Due to their bending flexibility, however, such hoses tend to kink, particularly at the points of connection to devices such as vacuum cleaner housings, but also when the hose is pulled around corners under considerable tensile load. When this happens, constrictions of the cross section occur, which reduce the suction power. Lasting deformations or damage to the hose may also be caused when kinking occurs.
All the known anti-kink device support the hose from outside, i.e. at the helically running ribs, and are designed as tubular grommets which are fixed to the device and through which the hose is passed. Cage-like supporting structures are also known for this purpose.
Supporting coils made from steel wire have also been proposed, which enclose the hose from outside and run in the opposite direction to that of the helical ribs, i.e. if the ribs are designed in the manner of thread to the left then the windings of the supporting coil run in the manner of a thread to the right. The known anti-kink device lack the stabilizing effect to protect the hose against the tendency to collapse when subjected to bending loads, as a result of which throughflow losses may arise.
What is needed is to provide an anti-kink device for hoses, in particular vacuum cleaner hoses, which can protect the hose at all critical points against kinking and collapsing, without significantly reducing the bending flexibility at these points.